Export-import API for rates and booking

System now has API for (automated) export-import of rates and booking dates for vacation rentals. Right now API output and accept data as comma-separated values format.

Site's layout changed a bit to separate growing business control links from user's controls. Decreased amount of business elements on interface for regular users - now it's just "add vacation rentals", "add travel experience" and "create website". Much more business-related options appears in menu after user add any of "business elements" to the site - API, agents*, site's custom pages, orders*, leads, etc. etc.